newtonian world and astrophysics (fill in gaps in astrophysics)

absolute zero

the temperature at which a substance has minimum internal energy and kinetic energy of the particles is zero - 0K and -273.15C

thermal equilibrium

objects in contact with each other at the same temperature

particles in a solid

vibrate about a fixed position - strong forces between them

particles in a liquid

can slide past each other - weaker attractive forces

particles in a gas

particles move quickly in random directions very weak forces of attraction

equation of density for molecules

density = mass of one molecule x number of molecules per cubic meter

internal energy

the sum of the randomly distributed kinetic and potential energies of the atoms or molecules within a system

Brownian motion

The random movement of small visible particles suspended in a fluid

specific heat capacity

the amount of energy needed to raise the temperature of 1kg of the substance by 1 K

specific latent heat of fusion

the amount of energy required to change the phase of 1 kg of a substance from solid to liquid

specific latent heat of vaporisation

the amount of energy required to change the phase of 1 kg of a substance from a liquid to a gas

n

number of moles

N

number of particles

number of particles from the number of moles

N=n x N_A

ideal gas

a gas that has internal energy only in the form of random kinetic energy

the 6 assumptions when modelling ideal gases

1. the gas contains a large number of particles

2. the particles move rapidly and randomly

3. all collisions are perfectly elastic

4. there are negligible forces between particles except during collisions

5. the time for collisions is negligible compared to the time between collisions

6. particles have a negligible volume compared to the volume of gas in the container

Boyles law

the volume of a fixed mass of gas is inversely proportional to the pressure exerted on the gas, under conditions of constant temperature - pV = constant

pressure temperature law

at constant volume, the pressure of a gas is directly proportional to its absolute temperature. P/T= constant

Charles’ law

at constant pressure, the volume of a gas is directly proportional to its absolute temperature - V/T = constant

when will a real gas act like an ideal gas

• temperature is high, well above the boiling point of the gas

• pressure is low, so that the particles are far apart

k=

R/N_A

angular velocity

the rate of angular rotation, measured in radians per second, symbol (omega)

centripetal acceleration

the acceleration of an object moving with uniform circular motion

centripetal force

the resultant force on an object, acting towards the centre of the circle, causing it to move in a circular path

displacement (SHM)

the distance an object moves from its equilibrium position

Amplitude (SHM)

the maximum displacement

SHM

a body oscillating in such a way that its acceleration is directly proportional to its displacement from its equilibrium position and always directed towards that point

a use for damping

shock absorbers in car suspension

natural frequency

the frequency at which a system will oscillate when undergoing free oscillations

resonance

when the driving frequency is equal to the natural frequency of a system resulting in it oscillating at maximum amplitude

the two effects of increasing the amount of damping on an object undergoing resonance

• reduces amplitude

• reduces the frequency that coresponds to the maximum amplitude of the oscillation

a practical use of resonance

microwave ovens

a harmful effect of resonance

dangers in buildings or bridges caused by wind or earthquakes

gravitational field

the region around a body in which other bodies will feel a force due to the mass of the body

newtons law of gravitation

the gravitational force between two masses is directly proportional to the product of their masses and inversely proportional to the square of their separation

keplers first law

planets travel around the sun in elliptical orbits

keplers second law

a line joining the sun to a planet will sweep out equal areas in equal times

keplers third law

the time period of the orbit squared is proportional to the mean of the radius of cubed

geostationary orbit

an orbit that has the same time period and orbital rotatdirection as the rotation of the earth and is in the orbital plane

one use for geostationary satellites

• broadcasting tv signals

• Monitoring the weather

• Monitoring air traffic

gravitational potential

the work done in moving a mass in a gravitational field to the point it is at from infinity

escape velocity

the minimum launch velocity required to move a object from that point to infinity

nuclear fusion

the process of two nuclei joining together and releasing energy

comet

a large rocky ice ball that travel in highly elliptical orbits around the sun

gravitational collapse

the inward movement of a star due to the gravitational force caused by its own mass

radiation pressure

an outward acting force caused by fusion reaction

gas pressure

outward acting force caused by the kinetic energy of the gas particles

features of a white dwarf

very dense with high surface temperature an low luminosity

electron degeneracy pressure

the pressure that stops the gravitational collapse of a low mass star

Chandrasekhar limit

the maximum possible mass for a stable white dwarf

luminosity

the total energy a star produces per second

basic initial stages for formation of any star

1. nebula (giant cloud of hydrogen gas)

2. protostar (hotter and glowing)

3. Main sequence star (inward and outward forces in equilibrium)

evolution of a low mass star

1. red giant (expanded and cooled)

2. Planetary nebula (outer layers of gas that have been ejected)

3. white dwarf (hot, dense core)

4. Black dwarf ( no longer emiting heat or light)

evolution of high mass stars

1. Red super giant (expanded and cooled)

2. supernova (High temperatures fusing heavy nuclei beyond iron)

3. neutron star (the neutron core has remained intact)

4. black hole (escape velocity is so high that photons are unable to escape, dense singularity)

3 and 4 both evolve from supernova not in order

HR diagram

wiens law

the product of the maximum wavelength and temperature is constant

stefans law

The total energy emitted by a black body per unit area per second is proportional to the fourth power of the absolute temperature of the body

• Stefan's Law equation is given by:

L = 4πr²σT⁴

AU

Mean distance from the centre of the earth to the centre of the sun

stellar parallax=

p=1/d d is distance in parsecs

Hubbles law

the recessional velocity of a galaxy is proportional to its distance from the earth

the cosmological principle

on a large scale the universe is both homogenous and isotropic

The big bag theory

states that the universe was created from a singularity where all of the universes current mass was situated. It was much smaller, hotter and denser then it is now

isotropic

the same in all direction

homogeneous

of uniform density

timeline of the universe

10^-35 - rapid expansion, high energy gamma photons and em waves

10^-6 - 1st fundamental particles gain mass

10^-3 - 1st hadrons come from quarks

1s - production of mass halted

100s - pprotons and neutrons fuse to become light nuclei

380,000 years - first atoms form

30mil years - 1st stars form, fusion of heavier elements

200mil - our galaxy forms

13.7bill years - current life as we know it

dark matter

matter which can not be seen and that does not emit or absorb e.m. radiation

Dark energy

A type of energy that permeates the whole universe and opposes the attractive force of gravitation between galaxies

three possible outcomes of the universe

open universe - keeps expanding forever

flat universe - stops expanding at a certain size and stays in equilibrium

closed universe - ‘Big crunch’, the universe will eventually collapse in on itself